BIOL BC 1500x Chapter Notes - Chapter 44: Gastrovascular Cavity, Hemolymph, B Cell
29 Sep 2016
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Circulatory system is needed for animals which are too large and complex for diffusion to deliver materials. Materials diffuse across surfaces open to environment (external surface or inside of tubes or cavities) Sponges: pores (beaten by flagella) -> central cavity -> exit pore. Cnidarians: gastrovascular cavity where water circulates materials by entering and leaving mouth. Returns to heart via veins or directly through ostia (pores) High activity animals with ocs (insects) have adaptations like trachea. Allows animal to have more control over distribution and speed of blood flow. Blood goes ventricle -> arteries -> capillaries in gills -> arteries -> capillaries in body tissues -> veins -> atrium. Going through to capillary networks before going back to heart lowers pressure, less. Keeps blood with oxygen partially separate from deoxygenated blood. Oxygenated blood enters left atria from blood and skin (pulmocutaneous circuit) Deoxygenated blood enters right atria from body tissues (systemic circuit) Blood pumped to ventricle, stays about 90% separate.
